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    <h1>导航条</h1>
    <p>
        <a href="https://www.bing.com" target="mainFrame">必应</a><br>
        <a href="https://www.taobao.com" target="mainFrame">淘宝</a><br>
        <a href="https://www.sina.com.cn" target="mainFrame">新浪</a><br>
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